Regulated vacuum off-gassing of gas filter for fluid processing system and related methods

ABSTRACT

A method for filtering a gas includes delivering a gas into a compartment of a gas filter assembly; applying a partial vacuum to the gas filter assembly so that the partial vacuum assists in drawing the gas through a porous filter body of the gas filter assembly that is at least partially disposed within the compartment of the gas filter assembly; and regulating the application of the partial vacuum based on a pressure reading of the gas upstream of the gas filter assembly.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/249,781, filed Aug. 29, 2016, which is a continuation of U.S.application Ser. No. 14/508,824, filed Oct. 7, 2014, now U.S. Pat. No.9,457,306, which are incorporated herein by specific reference.

BACKGROUND OF THE INVENTION 1. The Field of the Invention

The present invention relates to fluid processing systems and relatedgas filtering systems that apply a partial vacuum on a downstream sideof the gas filter.

2. The Relevant Technology

Bioreactors are used in the growth of cells and microorganisms. Atypical bioreactor includes a container which holds a culture comprisedof liquid growth media, cells or microorganisms, and other desirednutrients and components. A rotatable impeller is operated within theculture to maintain the culture in a substantially homogenous state.Small gas bubbles are continuously sparged into the culture and aretypically used to help oxygenate the culture, strip out unwanted CO₂from the culture and control the pH of the culture.

To maintain the viability of the cells/microorganisms, the compartmentin which the culture is being grown must remain sterile. To remove thesparged gas that is being continuously added to the culture whilemaintaining sterility of the compartment, the gas is typically exhaustedto the environment through a gas filter system. One conventional gasfilter system is referred to as a cartridge filter system and includes arigid, metal housing into which a cartridge filter is removablypositioned. Gas from the container is delivered to any inlet on thehousing. The gas then travels through the filter within the housing andis then expelled to the environment through an outlet on the housing.The filter prevents any biological matter within the container frombeing expelled into the environment and prevents any contaminates in theenvironment from entering into the container. Capsule filters are alsoused with bioreactors. A capsule filter comprises a rigid plastichousing that permanently encases a filter. Again, the gas is passedthrough the capsule filter and then expelled to the environment. Capsulefilters have a benefit in that they are disposable and thus do not needto be cleaned or sterilized after use.

Although conventional cartridge filter systems and capsule filters usedon bioreactors are useful, they have a number of shortcomings. Forexample, conventional cartridge filter systems and capsule filterstypically have a relatively small inlet port and outlet port throughwhich the gas passes. As such, to obtain desired gas flow rates throughthe filter systems, it can be necessary to operate the system at anelevated gas pressure. Many current bioreactors, however, comprise aflexible bag in which the culture is grown. Such flexible bags cannotoperate at elevated gas pressures or they will rupture. To enableoperating at a low gas pressure but at a high gas flow rate, somebioreactors use multiple gas filters in parallel to filter the gas.However, gas filters are very expensive and the required use of multiplefilters on a single bioreactor is a significant cost to the system.

Accordingly, what is needed in the art is gas filtering systems that canbe used with bioreactors that help optimize the use of gas filters toreduce costs. In some embodiments, it would also be advantageous to havesuch gas filtering systems that enable operating at relatively low gaspressures.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present invention will now be discussed withreference to the appended drawings. It is appreciated that thesedrawings depict only typical embodiments of the invention and aretherefore not to be considered limiting of its scope.

FIG. 1 is a schematic view of one embodiment of an inventive fluidprocessing system;

FIG. 2 is a perspective view of an alternative embodiment of a gasfilter system that can be used in the fluid processing system depictedin FIG. 1;

FIG. 3 is a cross sectional side view of the gas filter system depictedin FIG. 2;

FIG. 3A is a cross sectional side view of an alternative embodiment ofthe gas filter system depicted in FIG. 3;

FIG. 4 is a partially exploded view of the gas filter system depicted inFIG. 2;

FIG. 5 is a schematic view of a plurality of gas filter systems that canbe used with the fluid processing system depicted in FIG. 1;

FIG. 6 is a perspective view of an alternative embodiment of a gasfilter system that can be used with the fluid processing system depictedin FIG. 1;

FIG. 7 is a schematic view showing a plurality of different fluidprocessing systems 10 operating with a central vacuum source; and

FIG. 8 is a chart showing comparative data of gas flow through filterswith and without applied negative pressure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Before describing the present disclosure in detail, it is to beunderstood that this disclosure is not limited to particularlyexemplified apparatus, systems, methods, or process parameters that may,of course, vary. It is also to be understood that the terminology usedherein is only for the purpose of describing particular embodiments ofthe present invention, and is not intended to limit the scope of theinvention in any manner.

All publications, patents, and patent applications cited herein, whethersupra or infra, are hereby incorporated by reference in their entiretyto the same extent as if each individual publication, patent, or patentapplication was specifically and individually indicated to beincorporated by reference.

The term “comprising” which is synonymous with “including,”“containing,” or “characterized by,” is inclusive or open-ended and doesnot exclude additional, unrecited elements or method steps.

It will be noted that, as used in this specification and the appendedclaims, the singular forms “a,” “an” and “the” include plural referentsunless the content clearly dictates otherwise. Thus, for example,reference to a “port” includes one, two, or more ports.

As used in the specification and appended claims, directional terms,such as “top,” “bottom,” “left,” “right,” “up,” “down,” “upper,”“lower,” “proximal,” “distal” and the like are used herein solely toindicate relative directions and are not otherwise intended to limit thescope of the invention or claims.

Where possible, like numbering of elements have been used in variousfigures. Furthermore, multiple instances of an element and orsub-elements of a parent element may each include separate lettersappended to the element number. For example two instances of aparticular element “91” may be labeled as “91a” and “91b”. In that case,the element label may be used without an appended letter (e.g., “91”) togenerally refer to instances of the element or any one of the elements.Element labels including an appended letter (e.g., “91a”) can be used torefer to a specific instance of the element or to distinguish or drawattention to multiple uses of the element. Furthermore, an element labelwith an appended letter can be used to designate an alternative design,structure, function, implementation, and/or embodiment of an element orfeature without an appended letter. Likewise, an element label with anappended letter can be used to indicate a sub-element of a parentelement. For instance, an element “12” can comprise sub-elements “12a”and “12b.”

Various aspects of the present devices and systems may be illustrated bydescribing components that are coupled, attached, and/or joinedtogether. As used herein, the terms “coupled”, “attached”, and/or“joined” are used to indicate either a direct connection between twocomponents or, where appropriate, an indirect connection to one anotherthrough intervening or intermediate components. In contrast, when acomponent is referred to as being “directly coupled”, “directlyattached”, and/or “directly joined” to another component, there are nointervening elements present. Furthermore, as used herein, the terms“connection,” “connected,” and the like do not necessarily imply directcontact between the two or more elements.

Various aspects of the present devices, systems, and methods may beillustrated with reference to one or more exemplary embodiments. As usedherein, the term “exemplary” means “serving as an example, instance, orillustration,” and should not necessarily be construed as preferred oradvantageous over other embodiments disclosed herein.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which the present disclosure pertains. Although a number ofmethods and materials similar or equivalent to those described hereincan be used in the practice of the present disclosure, the preferredmaterials and methods are described herein.

The present invention relates to fluid processing systems where a fluid,such as a solution and/or suspension, is sparged with a gas and aresulting exhaust gas must subsequently be filtered. The presentinvention also relates to filter systems that can be used as part of thefluid processing systems and methods for using the forgoing systems. Thefluid processing systems can comprise bioreactors or fermenters used forculturing cells or microorganisms. By way of example and not bylimitation, the inventive systems can be used in culturing bacteria,fungi, algae, plant cells, animal cells, protozoans, nematodes, and thelike. The inventive systems can accommodate cells and microorganismsthat are aerobic or anaerobic and are adherent or non-adherent. Thesystems can also be used in association with the formation and/ortreatment of solutions and/or suspensions that are not biological butnevertheless incorporate sparging and gas filtration. For example, thesystems can be used in the production of media, chemicals, foodproducts, medicines, beverages, and other liquid products that requiresparging with a gas.

The inventive systems can be designed so that a majority of the systemcomponents that contact the material being processed are disposed ofafter a single use. As a result, the inventive systems substantiallyeliminate the burden of cleaning and sterilization required byconventional stainless steel mixing and processing systems. This featurealso ensures that sterility can be consistently maintained duringrepeated processing of multiple batches. In view of the foregoing, andthe fact that the inventive systems are easily scalable, relatively lowcost, and easily operated, the inventive systems can be used in avariety of industrial and research facilities that previously outsourcedsuch processing.

Depicted in FIG. 1 is one exemplary embodiment of an inventive fluidprocessing system 10 incorporating features of the present invention.Fluid processing system 10 comprises a rigid support housing 12 boundinga chamber 14. Support housing 12 can be scaled to any desired size. Forexample, it is envisioned that support housing 12 can be sized so thatchamber 14 can hold a volume of less than 50 liters, more than 5,000liters, or a volume therebetween. Support housing 12 is typically madeof metal, such as stainless steel, but can also be made of othermaterials capable of withstanding the applied loads of the presentinvention. Where needed, support housing 12 can be jacketed to permitheated or cooled fluid to be pumped therethrough for regulating thetemperature of the fluid housed within chamber 14 of support housing 12,as discussed below.

Disposed within support housing 12 is a container 16 that bounds acompartment 18. In one exemplary embodiment, container 16 comprises aflexible bag. Container 16 can be comprised of a flexible, waterimpermeable material such as a low-density polyethylene or otherpolymeric sheets or film having a thickness in a range between about 0.1mm to about 5 mm with about 0.2 mm to about 2 mm being more common.Other thicknesses can also be used. The material can be comprised of asingle ply material or can comprise two or more layers which are eithersealed together or separated to form a double wall container. Where thelayers are sealed together, the material can comprise a laminated orextruded material. The laminated material comprises two or moreseparately formed layers that are subsequently secured together by anadhesive.

In one embodiment, container 16 comprises a two-dimensional pillow stylebag wherein two sheets of material are placed in overlapping relationand the two sheets are bounded together at their peripheries to formcompartment 18. Alternatively, a single sheet of material can be foldedover and seamed around the periphery to form the internal compartment.In another embodiment, container 16 can be formed from a continuoustubular extrusion of polymeric material that is cut to length and isseamed closed at the ends. In still other embodiments, container 16 cancomprise a three-dimensional bag that not only has an annular side wallbut also a two dimensional top end wall and a two dimensional bottom endwall.

It is appreciated that container 16 can be manufactured to havevirtually any desired size, shape, and configuration. For example,container 16 can be formed having a compartment sized to 10 liters, 30liters, 100 liters, 250 liters, 500 liters, 750 liters, 1,000 liters,1,500 liters, 3,000 liters, 5,000 liters, 10,000 liters or other desiredvolumes. The size of the compartment can also be in the range betweenany two of the above volumes. Although in the above discussed embodimentcontainer 16 has a flexible, bag-like configuration, in alternativeembodiments it is appreciated that container 16 can comprise any form ofcollapsible container or semi-rigid container. In some embodiments,container 16 can comprise a rigid container, such as comprised of metal,molded plastic or a composite. In this embodiment, support housing 12can be eliminated as container 16 is self-supporting.

Ports 20 can be coupled to container 16 so as to communicate withcompartment 18. Any desired number of ports 20 can be used and they canbe positioned at any location on container 16. Ports 20 can be the sameconfiguration or different configurations and can be used for a varietyof different purposes. For example, ports 20 can be coupled with fluidlines for delivering media, cell cultures, and/or other components intoand out of container 16. Ports 20 can also be used for coupling probesto container 16. For example, when container 16 is used as a bioreactorfor growing cells or microorganisms, ports 20 can be used for couplingprobes and sensors such as temperature probes, pH probes, dissolvedoxygen probes, pressure sensors and the like. Examples of ports 20 andhow various probes and lines can be coupled thereto is disclosed inUnited States Patent Publication No. 2006-0270036, published Nov. 30,2006 and United States Patent Publication No. 2006-0240546, publishedOct. 26, 2006, which are incorporated herein by specific reference.Ports 20 can also be used for coupling container 16 to secondarycontainers and to other desired fittings.

In one embodiment of the present invention, means are provided fordelivering a gas into the lower end of container 16. By way of exampleand not by limitation a sparger 22 can be either positioned on ormounted to a lower end of container 16 for delivering a gas to a fluid24 disposed within container 16. In the present embodiment, fluid 24comprises a culture that includes cells or microorganisms. In otherembodiments, however, fluid 24 can comprise other solutions, suspension,or liquids as discussed herein. As is understood by those skilled in theart, various gases are typically required in the growth of cells ormicroorganisms within container 16. The gas typically comprises air thatis selectively combined with oxygen, carbon dioxide and/or nitrogen.However, other gases can also be used. The addition of these gases canbe used to regulate the dissolved oxygen and CO₂ content and to regulatethe pH of a culture solution. Depending on the application, spargingwith gas can also have other applications. A gas line 26 extends from agas source 28 to sparger 22 for delivering the desired gas to sparger22.

Sparger 22 can have a variety of different configurations. For example,sparger 22 can comprise a permeable membrane or a fritted structurecomprised of metal, plastic or other materials that dispense the gas insmall bubbles into container 16. Smaller bubbles can permit betterabsorption of the gas into the fluid. In other embodiments, sparger 22can simply comprise a tube, port, or other type opening formed on orcoupled with container 16 through which gas is passed into compartment18. Examples of spargers and how they can be used in the presentinvention are disclosed in United States Patent Publication Nos.2006-0270036 and 2006-0240546 which are incorporated by reference. Otherconventional spargers can also be used.

In one embodiment of the present invention, means are provided formixing fluid 24 contained within container 16. By way of example and notby limitation, an impeller 30 or other mixing element is disposed withincompartment 18. Impeller 30 is rotated by a drive shaft that projectsinto container 16 through a dynamic seal 34. External rotation of driveshaft 32 thus facilitates rotation of impeller 30 which mixes fluid 24within container 16.

In another embodiment, drive shaft 32 can project into container 16through a flexible tube having one end rotatably connected to container16 and an opposing second end connected to impeller 30. Drive shaft 32passes through the flexible tube and removably couples with impeller 30so that drive shaft 32 can rotate impeller 30 without directlycontacting fluid 24. Examples of this mixing system are disclosed inU.S. Pat. No. 7,384,783, issued Jun. 10, 2008 and U.S. Pat. No.7,682,067, issued Mar. 23, 2010 which are incorporated herein byspecific reference. In another alternative embodiment, drive shaft 32can be configured to repeatedly rise and lower a mixing element locatedwithin container 16 for mixing the fluid. Alternatively, a magnetic stirbar or impeller can be disposed within compartment 18 of container 16and rotated by a magnetic mixer disposed outside of container 16. In yetother embodiments, a stir bar, paddle, or the like that projects intocompartment 18 of container 16 can be pivoted, swirled, shook orotherwise moved to mix fluid 24. In addition, the mixing can beaccomplished by circulating fluid through compartment 18, such as byusing a peristaltic pump to move the fluid into and out of compartment18 through a tube having opposing ends sealed to container 16. Gasbubbles can also be passed through the fluid to achieve the desiredmixing. Finally, support housing 12 and container 16 can be pivoted,rocked, rotated or otherwise moved so as to mix fluid 24 withincontainer 16. Other conventional mixing techniques can also be used.Specific examples of how to incorporate a mixer into a flexible bag,such as container 16, are disclosed in U.S. Pat. No. 7,384,783, issuedJun. 10, 2008; U.S. Pat. No. 7,682,067, issued Mar. 23, 2010; and USPatent Publication No. 2006/0196501, issued Sep. 7, 2006 which areincorporated herein by specific reference.

Coupled with container 16 is a pressure sensor 33 that is used to sensethe gas pressure within compartment 18. Specifically, during use a headspace 25 is formed above fluid 24. Pressure sensor 33 is positioned soas to be disposed within or otherwise communicate with head space 25 soas to sense the pressure therein. It is appreciated that anyconventional pressure sensor can be used. Pressure sensor 33 can becoupled with a transmitter 35 for transmitting readings from pressuresensor 33 to a computer processor 190. Alternatively, pressure sensor 33can be wired to computer processor 190. The operation of pressure sensor33 and computer processor 190 will be discussed below in greater detail.

Although not required, in one embodiment of the present invention acondenser system 36 is coupled with container 16 for condensing themoisture that escapes from container 16 with the exhaust gas. Ingeneral, condenser system 36 comprises a condenser 38, a condenser bag40, a chiller 42, and a pump 44. More specifically, condenser bag 40comprises a two or three dimensional flexible bag made from one or moresheets of polymeric film, such as the materials discussed above withregard to container 16. Condenser bag 40 has an inlet end 46 and anopposing outlet end 47. Inlet end 46 is fluid coupled with compartment18 of container 16 such as by being directly coupled to an upper end ofcontainer 16 or, as depicted, by a gas line 48 extending from the upperend of container 16 to inlet end 46. Gas line 48, as with all of theother gas lines and fluid lines discussed herein, can comprise flexibletubing, a tube comprised of film, a rigid conduit or other conduits.Formed between inlet end 46 and outlet end 47 of condenser bag 40 is acatch 50, typically having a U-shaped configuration. As discussed below,moisture condensed within condenser bag 40 collects at catch 50.

A fluid line 52 has a first end coupled with catch 50 and an opposingsecond end coupled with either container 16 or a separate fluidreservoir. As such, fluid line 52 can be used to either return thecondensed moisture back to container 16 or to collect the condensedmoisture within the fluid reservoir for subsequent use or disposal.Depending on the position and configuration of condenser bag 40, thecondensed moisture can either freely flow through fluid line 52 underthe force of gravity or can be pumped through fluid line 52 such as byattaching a peristaltic pump to fluid line 52. In another alternativeembodiment, the second end of fluid line 52 can be coupled with gas line48 or to inlet end 46 of condenser bag 40 so that the fluid deliveredthere will then flow down into container 16.

Condenser 38 comprises a pair of panels 54A and 54B that each bound afluid path that extends therethrough. Each panel 54 has an inletcommunicating with the fluid path and coupled with a fluid line 56 andan outlet communicating with the fluid path and coupled with a fluidline 58. The opposing ends of fluid lines 56 and 58 communicate withchiller 42. Specifically, a fluid is chilled by chiller 42 and thenpumped by pump 44 through fluid line 56, through the fluid path withinpanel 54 and then back to chiller 42 through fluid line 58 where theprocess is then repeated. Panels 54 are typically comprised of a metal,such as aluminum, or some other high thermally conductive material. Assuch, passing the chilled fluid through panels 54 causes panels 54 tocool. Panels 54 typically have a substantially flat inside face 60 thatis disposed directly against opposing side faces of condenser bag 40.Accordingly, as humid gas is passed through condenser bag 40, the humidgas is cooled by heat transfer with panels 54 such that the moisturewithin the humid gas condenses into a liquid that collects at catch 50,as discussed above. Specific examples of each of the components ofcondenser system 36, how condenser bag 40 can fluid couple withcontainer 16, how the liquid from the condensed moisture can be returnedto container 16 and alternative embodiments of condenser systems thatcan be used in the present invention are disclosed in U.S. Pat. No.8,455,242, issued Jun. 4, 2014 and US Patent Publication No.2015/0265943, published Sep. 24, 2015, which are incorporated herein byspecific reference. Other conventional condenser systems can also beused.

In alternative embodiments, it is appreciated that condenser system 36can comprise any conventional condenser system that can be used tocondense moisture from a gas. Such conventional systems typically do notinclude a condenser bag 40 but often have rigid or semi-rigid conduitsthrough which the gas passes and which are located within or directlyadjacent to a cooling source.

In view of the foregoing, during use fluid 24 is dispensed intocompartment 18 of container 16. As previously discussed, fluid 24 cancomprise a culture of cells or microorganisms along with media,nutrients, and other desired components or, alternatively, other typesof fluids that require processing. Where the fluid must remain sterile,container 16, and specifically compartment 18 thereof, is sterilized,such as by radiation, prior to use. Gas bubbles 23 are sparged intofluid 24 through sparger 22. Concurrently, impeller 30 or some othermixing element is operated so as to mix fluid 24 and typically maintainit substantially homogenous. Gas bubbles 23 pass through fluid 24 makinga mass transfer therewith and then collect within head space 25 locatedat an upper end of container 16. As the gas pressure increases, thesparged gas which is humid travels into condenser bag 40 through gasline 48. Moisture within the humid gas is condensed by condenser 36 andreturned to container 16 or delivered to some other fluid reservoir aspreviously discussed.

The now dehumidified gas passes out of outlet end 47 of condenser bag 40and travels to an intake port 64A of a filter assembly 66A. Condenserbag 40 can be directly coupled to filter assembly 66A, such as bydirectly coupling together ports located on condenser bag 40 and filterassembly 66A, or can be fluid coupled together by a gas line 68extending therebetween, as depicted. In other embodiments, condensersystem 36 can be eliminated so that filter assembly 66A couples withcontainer 16 either directly or through a gas line.

In one exemplary embodiment, filter assembly 66A comprises a casing 70Athat bounds a compartment 72. Disposed within compartment 72 is a filter74A. The gas from gas line 68 enters compartment 72 through intake port64A, passes through filter 74A and then exits through an exhaust port65A. As such, all of the gas passing through filter assembly 66A passesthrough filter 74A. In one embodiment, filter 74A can comprise acartridge filter while casing 70A comprises a rigid housing, such as ametal housing, in which the cartridge filter can be removably received.In an alternative embodiment, filter assembly 66A can comprise a capsulefilter wherein filter 74A is permanently enclosed within a rigid outercasing, such as a polymeric casing.

Filter 74A is typically made of a porous material through which gas canpass but through which unwanted contaminants, such as bacteria andmicroorganisms, cannot. The porous material is typically hydrophobicwhich helps it to repel liquids. For example, filter 74A can becomprised of polyvinylidene fluoride (PVDF). Other materials can also beused. Where the system is acting as a bioreactor or fermentor, filter74A typically needs to operate as a sterilizing filter and will thustypically have a pore size of 0.22 micrometers (μm) or smaller. The term“pore size” is defined as the largest pore in the material through whicha particle can pass. Commonly, filter 74A has a pore size in a rangebetween 0.22 and 0.18 μm. However, for pre-filtering applications or fornon-sterile applications, filter 74A can have a larger pore size, suchas in a range between about 0.3 and 1.0 μm. In still other applications,the pore size can be greater than 1.0 μm. One example of filter 74A isthe DURAPORE 0.22 μm hydrophobic cartridge filter produced by Millipore.Another example is the PUREFLO UE cartridge filter available fromZenPure.

Depicted in FIG. 2 is a filter assembly 66B which is an alternativeembodiment of and can be used in place of filter assembly 66A. Filterassembly 66B comprises a casing 70B having an intake port 64B mounted atone end and an exhaust port 65B mounted on an opposing end. Casing 70Bcomprises a flexible, collapsible bag comprised of one or more sheets ofpolymeric material such as polymeric film. Casing 70B can be comprisedof the same materials and be produced using the same manufacturingmethods as previously discussed above with regard to container 16. Inthe depicted embodiment, casing 70B comprises a pillow type bag that ismanufactured from two overlapping sheets of polymeric film that areseamed together along perimeter edges. In some applications, filterassembly 66, condenser bag 40, container 16 and the gas lines thatextend therebetween can all be sterilized prior to use.

As depicted in FIG. 3, casing 70B has an interior surface 96 and anopposing exterior surface 98. Interior surface 96 bounds a compartment100. Casing 70B has a first end 101 at which an inlet opening 102 isformed. Inlet opening 102 is configured to be coupled with intake port64B. Casing 70B also has an opposing second end 103 at which an outletopening 104 is formed. Outlet opening 104 is configured to be coupledwith exhaust port 65B.

As depicted in FIG. 4, intake port 64B comprises a tubular stem 108 thatbounds a port opening 109 extending therethrough. An annular couplingflange 110 encircles and radially, outwardly projects from stem 108.Coupling flange 110 has an end face 106 (FIG. 3) with an annular seal107, such as an O-ring, disposed thereon. Stem 108 of intake port 64Bcan be secured to casing 70B by being received within inlet opening 102and welded to casing 70B so that coupling flange 110 is openly exposed.Port opening 109 thus communicates with compartment 100 of casing 70B. Aport identical to intake port 64B can be mounted at outlet end 47 ofcondenser bag 40. A sealed coupling between condenser bag 40 and filterassembly 66B can then be achieved by simply clamping the couplingflanges together, such as through the use of a tri-clamp.

Continuing with FIG. 4, exhaust port 65B comprises a tubular stem 114having an interior surface 116 and an opposing exterior surface 118extending between a first end 120 and an opposing second end 122. Formedon interior surface 116 at first end 120 is a connector. In the depictedembodiment, the connector comprises a pair of opposing bayonet slots 124(FIG. 3) formed on first end 120 so as to form half of a bayonetconnection. Interior surface 116 bounds a port opening 126 extendingthrough exhaust port 65B and which can have the same configurations anddimensions as port opening 109 of intake port 64B. Encircling andradially outwardly projecting from second end 122 of stem 114 is acoupling flange 128. An annular seal 129 is formed on an end face 131thereof. During attachment, first end 120 of stem 114 of exhaust port65B can be received within outlet opening 104 and welded to casing 70Bso that flange 128 is openly exposed.

Disposed within casing 70B is a filter 74B that is coupled with exhaustport 65B. As depicted in FIGS. 3 and 4, filter 74B comprises a filterbody 132 having an interior surface 134 and an exterior surface 136extending between a first end 138 and an opposing second end 140. Filterbody 132 includes a tubular side wall 142 that extends between opposingends 138 and 140 and a floor 144 disposed at second end 140. As such,interior surface 134 bounds a blind channel 146 that centrally extendsalong the length of filter body 132 but which is blocked at second end140 by floor 144. Upwardly projecting from first end 138 of filter body132 is a tubular neck 148. A pair of annular grooves 150A and B encirclethe exterior surface of neck 148 and are configured to receivecorresponding annular seals 152A and B. Also outwardly projecting fromthe exterior surface of neck 148 at a location below grooves 150A and Bare a pair of opposing bayonet prongs 154. An opening 156 extendsthrough neck 148 and communicates with channel 146. Filter body 132 canbe made from the same materials and have the same properties, includingpore size, as discussed above with regard to filter 74A.

During assembly, seals 152 are received within annular grooves 150following which neck 148 of filter 74B is coupled to exhaust port 65B bybayonet prongs 154 being received and rotated within bayonet slots 124.In this configuration, filter 74B is securely attached to exhaust port65B with seals 152 forming a gas tight seal between neck 148 andinterior surface 116 of exhaust port 65B. Next, filter 74B is slidwithin casing 70B so that exhaust port 65B is partially received withincasing 70B. A gas tight seal is then formed between casing 70B andexhaust port 65B such as by welding casing 70B to exterior surface 118of stem 114.

During use, as discussed below in more detail, gas from condenser bag 40or directly from container 16 enters filter assembly 66B at intake port64B but can only exit filter assembly 66B by passing through filter body132, traveling along channel 146 and then exiting out through exhaustport 65B. As such, filter 74B sterilizes or otherwise filters all gaspassing out of filter assembly 66B. Filter 74B also functions as asterilizing filter that prevent outside contaminates from accessing thecompartment of filter assembly 66B which could then potentially contactthe fluid 24 within container 16.

Filter assembly 66B is designed to be capable of filtering high flowrates of gas. Specifically, as gas enters filter assembly 66B, flexiblecasing 70B expands to the configuration shown in FIG. 3. In the expandedconfiguration, casing 70B is spaced apart from exterior surface 136 offilter body 132 along the length of filter body 132. As such, the gascan freely access and pass through filter body 132 from all sides andalong the full length of filter body 132, thereby optimizing the use offilter body 132 and maximizing the gas flow rate therethrough. In oneembodiment, the annular gap distance D between exterior surface 136 offilter body 132 and the interior surface of casing 70B is in a rangebetween about 0.15 cm to about 3 cm with between about 0.2 cm to about 1cm being more common. In some embodiments, the gap distance D can begreater than 1 cm or 2 cm. Other dimensions can also be used. In oneembodiment filter body 132 has a maximum transverse diameter in a rangebetween about 5 cm and about 10 cm. Other dimensions can also be used.Furthermore, gap distance D typically extends over at least 80% and morecommonly at least 90%, 95% or 100% of the length of filter body 132.Filter assembly 66B can also process a high gas flow rate because theport openings of intake port 64B and exhaust port 65B can be designedhaving a surprising large diameter, such as greater than 3 cm, 4 cm, 5cm or 6 cm. In addition, as discussed below, filter assembly 66B can bedesigned to simultaneously operate with a plurality of filters 74B thatare disposed in parallel communication with the gas flow.

The inventive fluid processing system 10, depending on the size thereof,can commonly operate at gas flow rates greater than 200 or 600 standardliters per minute (“slpm”) and depending on the size thereof, it isenvisioned that it can operate at gas flow rates greater than 2000,5,000 or 10,000 slpm. Of course, the system can also operate at lowerflow rates. Expressed in other terms, some embodiments of the systemcommonly operate at a gas flow rate between about 0.001 to about 2.5vessel volumes per minute (based on the volume of container 16) withabout 0.1 to about 1.0 vessel volumes per minute being more common.Other flow rates can also be used.

In one alternative embodiment, the filter and exhaust port can be formedas a single piece. For example, depicted in FIG. 3A is a filter 74C.Like elements between filter 74C and previously discussed filter 74B areidentified by like reference characters. Filter 74C includes filter body132 which has the same structure, composition and properties aspreviously discussed. However, rather than including neck 148 at firstend 138, filter 74C includes an exhaust port 65C that is permanentlyfixed to first end 138 of filter body 132, such as by over molding,adhesive, welding, or the like. As such, no separate seal is neededbetween exhaust port 65C and filter body 132.

Exhaust port 65C includes a stem 160 having an interior surface 162 andan opposing exterior surface 164 that extend between a first end 166 andan opposing second end 168. Second end 168 is secured to filter body 132as discussed above. Encircling and outwardly projecting from first end166 is a flange 170. Interior surface 162 bounds a port opening 172 thatextends therethrough and communicates with channel 146 of filter body132. Filter body 132 is received within casing 70B and exterior surface164 of exhaust port 65C is received within outlet opening 104 of casing70B. Exterior surface 164 is sealed to casing 70B, such as by welding,so as to form a gas tight seal. Exhaust port 164 is typically comprisedof a non-porous polymeric material while filter body 132 is comprised ofa porous material, as previously discussed.

In another embodiment, it is envisioned that exhaust port 65C could beeliminated and that casing 70B could be welded or otherwise secureddirectly to first end 138 of filter body 132. Further discussion onfilter assembly 66B, alternative embodiments thereto and how filterassembly 66B can be attached to condenser bag 40 and container 16 aredisclosed in US Patent Publication No. 2015/0265958, published Sep. 24,2015, which is incorporated herein by specific reference.

Also depicted in FIG. 4 is a heating jacket 198 that can be disposed oncasing 70A (FIG. 2) or casing 70B. Heating Jacket 198 includes aninsulation pad 200 that can be wrapped into a cylindrical loop and heldin the desired configuration by straps 202 that encircle the exterior ofpad 200. Disposed either within pad 200 or on the interior surfacethereof is an electrical heating element 204 such as heat tape or thelike. A hanger 206 can also project from the upper end of pad 200 byconnecting to either pad 200 or straps 202. During use, heating jacket198 is wrapped around a corresponding casing 70A, 70B. Jacket 198,however, is sized so that casing 70B can still inflate to provide thedesired gap between filter 74B and casing 70B but is also typicallyconfigured so that casing 70A, 70B push against the interior surface ofheating jacket 198 to produce an efficient heat transfer therebetween.Moisture that passes out of condenser system 36 and into filter assembly66 will collect on filters 74 and eventually clog the filters. Byactivating electrical heating element 204, heating jacket 198 assists toheat and vaporize the condensed liquid on filters 74 so that it can passthrough and out of filters 74, thereby prolonging the active life offilters 74.

Returning to FIG. 1, a transfer line 180 has a first end 181 coupledwith exhaust port 65 (i.e., exhaust port 65A or 65B) of filter assembly66 (i.e., filter assembly 66A or 66B) and an opposing second send 183coupled with a vacuum pump 185. Transfer line 180 can comprise flexibletubing, a rigid conduit, vacuum hose, or any other type of conduit thatcan operate under a negative pressure without fully collapsing. Duringoperation, vacuum pump 185 is activated which produces a partial vacuumor negative pressure within transfer line 180. The partialvacuum/negative pressure is applied to exhaust port 65 of filterassembly 66 which functions to help pull the exhaust gas through filter74. The applied negative pressure is typically less (i.e., morenegative) than 0 kPa and more commonly less than −0.5, −1, −5 or −10kPa. The maximum negative pressure is typically greater (i.e., morepositive) than −100 kPa and more commonly greater than −80, −50, −30 or−20 KPa. The applied negative pressure is thus commonly between −0.5 kPaand −80 kPa with between −0.5 kPa and −50 kPa or between −0.5 kPa and−20 kPa being more common. Other values can also be used. Likewise, thepressure differential across filter 74 between intake port 64 andexhaust port 65 is typically in the range between 0.5 kPa and 80 kPawith between 0.5 kPa and 50 kPa or between 0.5 kPa and 20 kPa or between0.5 kPa and 10 kPa being more common. Again, other values can also beused.

Applying a partial vacuum or negative pressure to exhaust port 65 offilter assembly 66 has been found to achieve a number of benefits. Forexample, because of the relative small pore size of filter 74, there isa substantial pressure loss as the gas passes through filter 74. Thiscan be problematic, however, where there is a need to sparge gas at ahigh flow rate through fluid 24. That is, filter 74 restricts the flowof gas through filter assembly 74. To enable the flow of gas passingthrough filter 74 to keep up with the flow of gas being sparged intofluid 24, one option is to increase the gas pressure on the upstreamside of filter 74 so as to more rapidly force the gas through filter 74.However, where casing 70B, condenser bag 40 and/or container 16 arecomprised of a polymeric film, they are typically designed to operate atan internal gas pressure under 10 kPA and typically in a range between0.1 kPa and 8 kPa with between 0.5 kPa and 5 kPa or between 0.5 kPa and2 kPa being more common. It is noted that that casing 70B, condenser bag40 and/or container 16 are designed to operate at some positive pressureso that they remain inflated. At gas pressures above 50 kPa or morecommonly 60 kPa or 70 kPa, the polymeric film and/or the seams formedtherewith can rupture, thereby allowing contamination to enter thesterile environment and eventually contaminate fluid 24. Accordingly,where casing 70, condenser bag 40 and/or container 16 are comprised of apolymeric film or otherwise have a lightweight structure, safe operatingconditions can preclude any significant elevation of the gas pressureupstream from filter 74.

Casing 70, condenser bag 40 and container 16 could be formed as a rigidstructures that safely withstand higher gas pressures. However, in somesituations there can be significant benefits in using casing 70,condenser bag 40 and/or container 16 where they are made from apolymeric film. For example, where casing 90, condenser bag 40 and/orcontainer 16 are formed from a polymeric film, they are easier toproduce and substantially less expensive than their rigid counterparts,thereby decreasing expense. Furthermore, because casing 70, condenserbag 40 and/or container 16 are relatively inexpensive to produce, theycan be disposed of after a single use. As a result, no cleaning orsterilization is required between batches and there is less risk of theprocess fluid becoming contaminated.

One alternative to increasing the gas pressure upstream of filter 74 isto fluid couple a plurality of filter assemblies 66 in parallel tocondenser system 36 so that the filter assemblies 66 can process the gasflow rate at a lower gas pressure. However, the problem with thisapproach is that filters 74 are very expensive. Thus, although thisapproach is feasible, it is desirable to minimize the number of filters74 that are used so as to lower costs.

In contrast to using the above approaches, the benefit of applying apartial vacuum or negative pressure to exhaust port 65 of filter 74 isthat the applied negative pressure increases the flow rate of gasthrough filter 74 and decreases the gas pressure upstream of filter 74.As such, casing 70, condenser bag 40 and/or container 16 can stillsafely be used in fluid processing system 10 where they are comprised ofpolymeric film because the system can operate at a lower pressure.Although in some embodiments, as discussed below, it may still benecessary to use a plurality of filters 74 in parallel to accommodatefor high flow rates of sparged gas, by applying a partialvacuum/negative pressure to the exhaust port of each filter 74,significantly fewer filters or smaller filters can be required, therebyminimizing costs. An additional benefit of applying a partialvacuum/negative gas pressure to exhaust port 65 of filter 74 is that itextends the productive life over which filter 74 can be used. That is,filter 74 can be used longer when the negative gas pressure is appliedto exhaust port 65 of filter 74. By using a filter longer, fewer orsmaller filters are required which helps to minimize costs. The abovebenefits are also achieved independent of the type of filter assembly,condenser system and fluid container used. That is, even if the filterassembly, condenser system and fluid container are formed as a rigidstructure that can operate at an elevated gas pressure, applying thenegative pressure to the exhaust port of the filter assembly will reducethe number or size of filters that are required.

The partial vacuum/negative pressure applied to exhaust port 65 byvacuum pump 185 is typically maintained at a value so that the gaspressure upstream from filter 74 is positive and within the preferredoperating range as previously discussed, i.e., typically between 0.1 kPaand 2 kPa. If the partial vacuum/negative pressure is too great, the gaspressure upstream from filter 74 can be negative or sufficiently lowthat casing 74B collapses against filter 70B, thereby restricting theflow of gas through filter 70B. Collapsing condenser bag 40 and/orcontainer 16 can also restrict gas flow and negatively affect otheroperating conditions. Where casing 70, condenser bag 40 and/or container16 are sufficiently rigid that they can withstand a negative pressurewithout collapsing, the applied partial vacuum/negative pressure can beincreased to produce a negative pressure within one or more of casing70, condenser bag 40 and container 16.

Vacuum pump 185 can come in a variety of different configurations and beused in a number of different ways to achieve the desired partialvacuum/negative pressures and maintain the desired gas flow rates.Vacuum pump 185 typically comprises a positive displacement pump such asa rotary vane pump or diaphragm pump. However, other types of pumps canalso be used.

Vacuum pump 185 can also comprise a variable displacement pump or afixed displacement pump. Variable displacement pumps can be directlycontrolled to adjust the partial vacuum they produce. In contrast, fixeddisplacement pumps only operate to produce a constant partial vacuum.The produced constant partial vacuum, however, can be regulated duringapplication by diverting the vacuum to ambient, e.g., adjusting thedelivery of a separate gas into the vacuum line. For example, wherevacuum pump 185 is a fixed displacement pump, a three-way control valve182 can be coupled with transfer line 180. An air particle filter 178 iscoupled with control valve 182 by way of a transfer line 179. As aresult, air from the surrounding environment can pass through airparticle filter 178, through transfer line 179 and then into transferline 180 by passing through control valve 182. Thus, although vacuumpump 185 may be producing a constant partial vacuum, by using controlvalve 182 to regulate the amount of air from the environment that enterstransfer line 180 through transfer line 179, the partial vacuum ornegative pressure applied to exhaust port 65 of filter 74 can beregulated. In contrast, where vacuum pump 185 is a variable displacementpump, control valve 182, transfer line 179 and air particle filter 178can be eliminated and the amount of partial vacuum produced by vacuumpump 185 can be regulated by directly controlling the operation ofvacuum pump 185.

In one embodiment, the amount of vacuum applied to exhaust port 65 offilter 74 can be manually regulated by inspecting a pressure gauge 189that is coupled with transfer line 180. That is, based on the reading ofpressure gauge 189, an operator can adjust the operation of vacuum pump185 or, where applicable, adjust control valve 182 so as to adjust theapplied partial vacuum.

In one alternative automated embodiment, vacuum pump 185, pressure gauge189 and/or control valve 182 can be electrically coupled with computerprocessor 190 which, as previously discussed, is also electricallycoupled with pressure sensor 33 that detects the gas pressure withincontainer 16. In this embodiment, computer processor 190 canautomatically adjust the applied partial vacuum based on inputs receivedfrom pressure gauge 189 and pressure sensor 33. For example, as fluidprocessing system 10 operates, filter 74 slowly starts to plug whichincreases the gas pressure upstream from filter 74. Furthermore, the gaspressure upstream from filter 74 can increase by increasing the flowrate of gas sparged into container 16. The gas pressure upstream fromfilter 74 can also vary as a result of start-up, shut-down and changesin operating conditions.

Computer processors 190 can be programmed to monitor the pressuredetected by pressure sensor 33 and to automatically adjust the operationof vacuum pump 185 and/or control valve 182 so that the gas pressurewithin container 16, condenser bag 40 and/or casing 70 is maintainedwithin the desired operating range. That is, as the pressure increaseswithin container 16, vacuum pump 185 can be adjusted to produce a highervacuum or control valve 182 can be adjusted to restrict the flow of airinto transfer line 180 and thereby also produce a higher vacuum. Inturn, increasing the partial vacuum applied to exhaust port 65 of filter74 increases the gas flow rate through filter 74 and thus lowers the gaspressure within container 16. It is appreciated that the gas pressuredetected by pressure sensor 33 attached to container 16 is alsoapproximately the gas pressure within condenser bag 40 and casing 70. Assuch, pressure sensor 33 can also be located at any position in the gasstream between the compartment of casing 70 (FIG. 3) and headspace 25 ofcontainer 16.

As also depicted in FIG. 1, a second vacuum pump 185A can coupled totransfer line 180 by a secondary line 194. Where needed, the appliedvacuum can be increased by opening a valve 195 on secondary line 194 andactivating second vacuum pump 185A. As needed, additional vacuum pumpscan similarly be attached to transfer line 180 either for capacity orredundancy. Valve 195 and second vacuum pump 185A can be electricallycoupled with computer processor 190 for automated operation.

As previously mentioned, a single filter 74 may not be capable ofprocessing all of the sparged gas while maintaining the pressureupstream of filter 74 within the desired range, even when the partialvacuum is applied to filter 74. This can in part be due to the fact thatfilter 74 progressively clogs during the fluid processing. Accordingly,a plurality of filters 74 can be fluid coupled in parallel to vacuumpump 185. Specifically, depicted in FIG. 5 are filter assemblies 66C,66D and 66E which can each be the same as filter assembly 66A or 66B, aspreviously discussed herein. In any embodiment, each filter assembly66C-D includes a separate filter 74 within a casing 70. In otherembodiments, other numbers of filter assemblies 66 can be used inparallel such as 2, 4, 5, or more. Each filter assembly 66C-D has anintake port 64 that couples with a corresponding tubular gas linesection 216A-C, respectively. In turn, each gas line section 216A-Cfluid couples with gas line 68. Gas line 68 can couple with condensersystem 36 or can directly couple with container 16. Each filter assembly66C-D also has an exhaust port 65 that couples with a correspondingtubular gas line section 218A-C, respectively. In turn, each gas linesection 218A-C fluid couples with transfer line 180. During use, two ormore of filter assembly 66C-D can operate concurrently for filtering gasfrom container 16 and receiving a partial vacuum/negative pressure fromvacuum pump 185. Alternatively, valves 220A-C can be coupled with gasline sections 218A-C, respectively, and electrically coupled withcomputer processor 190. The fluid processing system can initiallyoperate with gas only passing through one or more of filter assembly66C-D. However, as that filter or filters become plugged and thepressure increases within container 16, subsequent valves 220 can beopened by computer processor 190 so that the gas pressure upstream fromfilter assembly 66C-D is maintained within desired operating range.

Depicted in FIG. 6 is another alternative embodiment of a filterassembly 66F. Like elements between filter assembly 66F and 66B areidentified by like reference characters. Filter assembly 66F includes acasing 70C that comprises a manifold section 224 and four spaced apartsleeves 226A-D projecting therefrom. Casing 70C is comprised of apolymeric film and can be formed in the same way and from the samematerials as casing 70B previously discussed. Intake port 64B is coupledwith manifold section 224 while exhaust ports 65B1-65B4 are attached tothe free end of sleeves 226A-D, respectively. Each exhaust port65B1-65B4 can be the same as exhaust port 65B previously discussed.Attached to each exhaust port 65B1-65B4 so as to be received within acorresponding sleeve 226A-D is a filter 74B1-B4, respectively. Eachfilter 74B1-B4 can be the same as filter 74B previously discussed.

During use, intake port 64B is coupled with gas line 68 (FIG. 1) forreceive gas either directly from container 16 or through condensersystem 36. In turn, each exhaust port 65B1-65B4 is coupled with acorresponding gas line section which couples with transfer line 180 andwhich feeds to vacuum pump 185. As such vacuum pump 185 can apply anegative pressure to each of exhaust port 65B1-65B4 and correspondingfilters filter 74B1-B4. Filters 74B1-B4 can be used concurrently tofilter the gas. Alternatively, sleeves 226A-D can be selectively clampedclosed to prevent gas from passing therethrough and then subsequentlyopened. As such, filters 74B1-B4 can be used consecutively to filter gastherethrough. It is appreciated that filter assembly 66F can be formedwith 2, 3, or 5 or more sleeves with each sleeve housing a separatefilter 74.

Returning to FIG. 1, coupled with transfer line 180 at spaced apartlocations between filter assembly 66 and vacuum pump 185 is a valve 184,a trap 186 and a pressure sensor 188. Valve 184 is used to selectivelyrelease gas from gas line 180 when the pressure therein becomes positiveor exceeds a predetermined positive value. For example, if vacuum pump185 stops operating or transfer line 180 becomes closed or otherwiseblocked, gas pressure can build within casing 70 of filter assembly 66,condenser bag 40 and/or container 16, as applicable. As previouslydiscussed, elevated pressures within these structures can cause thepolymeric film and/or the seams formed therewith to rupture, therebyallowing contamination to enter the sterile environment and eventuallycontaminate fluid 24.

Valve 184 operates as a pressure release valve to automatically releasethe gas pressure so that there is no failure in the system. To that end,valve 184 can comprise a passive valve such as a check valve including aball check valve, diaphragm check valve, or swing check valve thatautomatically opens when a positive pressure or a predetermined positivepressure is reached. The gas passes through valve 184 and is thenexhausted to the environment. In other embodiments, valve 184 cancomprise an active valve that is operated by computer processor 190. Forexample, valve 184 can comprise an electric valve, pneumatic valve, orhydraulic valve which is electrically coupled with computer processor190. Processor 190 is programmed so that when the pressure within gasline 180 becomes positive or exceeds a predetermined positive value asmeasured by pressure sensor 188, computer processor 190 opens valve 184until the pressure within gas line 180 drops to an acceptable value.Valve 184 can then be automatically closed. The process can then berepeated as the pressure within gas line 180 again begins to elevate. Inother embodiments or in conjunction with the above, valve 184 canconfigured to automatically open when a positive pressure or apredetermined pressure is detected within gas line 180 such as throughpressure sensor 188 (discussed below) or some other pressure sensorcoupled with gas line 180. In still another embodiment, valve 184 cancomprise a manual valve such as a standard ball or gate valve which ismanually opened when the pressure within gas line 180 exceeds apredetermined valve.

Trap 186 is optional and is used to collect fluid that may condensewithin gas line 180. The condensed fluid retrieved from trap 186 can beheld in a storage vessel 192 for subsequent disposal or processing orcan be directly fed back to container 16 through a fluid line connectedto trap 186. Trap 186 helps to ensure that fluid condensed in transferline 180 is not unintentionally exhausted from the system and that thecondensed fluid does not destruct the down-stream values or pumps.

As previously mentioned, pressure sensor 188 senses the pressure withintransfer line 180. Pressure sensor 188 can be wired to computerprocessor 190. Alternatively, readings from pressure sensor 188 can beconveyed to computer processor 190 via a transmitter 187. Pressuresensor 188 can be used to control the operation of valve 184 asdiscussed above.

In one exemplary embodiment, a central vacuum source can be concurrentlycoupled in parallel to a plurality of different fluid processingsystems. For example, depicted in FIG. 7 is a system that comprisescentral vacuum source 408 coupled in parallel to fluid processingsystems 10A-10C. Central vacuum source 408 can comprise one or moreindividual vacuum pumps 185, as discussed above, that operate togetherto form a single vacuum source. In one application the vacuum source 408can be run continuously. Each fluid processing system 10A-10C comprisesa fluid containment system 400, an optional condenser system 402, afilter assembly 404 and a controller 406.

Fluid containment system 400 can comprise container 16, a means formixing the fluid within container 16 and the other elements and/oralternatives discussed above with regard to container 16. Condensersystem 402 can comprise condenser system 36 and the alternatives thereofdiscussed above and which operates with fluid containment system 400 inthe same way that condenser system 36 operates with container 16. Filterassembly 404 comprises filter assemblies 66 and the alternatives thereofdiscussed above which operates with condenser system 402 or directlywith fluid containment system 400 in the same way that filter assemblies66 operate with condenser system 36 or container 16. Controller 406comprises the alternative control systems discussed above, such asprocessor 190, valve 182 and pressure sensor 33, which are used toautomatically regulate the application of the partial vacuum fromcentral vacuum source 408 to filter assembly 404 based on the gaspressure within fluid containment system 400 or some other predeterminedvalue.

In contrast to having a separate controller 406 for each fluidprocessing system 10A-10C, a single controller 406 could regulate all offluid processing system 10A-10C. Furthermore, although FIG. 7 showsthree fluid processing systems 10A-10C operating with central vacuumsource 408, in other embodiments 2, 4, 5, 6 or more fluid processingsystems could operate with a single central vacuum source 408. The aboveconfiguration provides for a single, continuous vacuum source that canbe shared across a plurality of work stations in a facility and thuseliminates the need for separate vacuum pumps.

Tests were conducted to determine the expected improvements to gas flowcapacity through filters that could be achieved if a vacuum device wereapplied to the exhaust gas filter of a bioreactor.

Materials & Methods:

Samples of two different cartridge filter types were selected for thepurpose of comparison of normal flow verses vacuum assisted gasfiltration: 1) Meissner filter using polyvinyl difluoride (PVDF) having0.2 micron pore rating and 2.5 inch in designated length and 2) Zenpurefilter using polyethylene (PE) having 0.2 micron pore rating and 2 inchin designated length. The filters were housed within a stainless steelfilter housing. To mimic the off-gas flow of a bioreactor bag, a 500slpm Alicat mass flow controller (MFC) was used to meter a known flowrate of air into to the stainless steel filter housings. Pressure gaugeswere placed both before the filter (between MFC and filter) and afterthe filter (between the filter and the vacuum pump). Prior to filtertesting, the filtration assembly was evaluated without a filtercartridge loaded to verify that backpressure inherent in the assemblywould not distort the results and also with the exhaust line closed toconfirm the assembly was leak proof. One of each filter was tested undernormal gas flow where the gas passing through the filter was simplyexhausted to the atmosphere. One of each filter was also tested with aBecker VT4.40 rotary vane vacuum pump applying a negative pressure tothe outlet port of the filter housing. The vacuum pump generated 23 inHgof vacuum (−11.3 psi) of vacuum at dead head (full vacuum, no flow).During testing of actual gas flow the differential between inlet andoutlet of the filter was typically less than 3 psi (delta).

Results:

The results are set forth in the chart presented as FIG. 8 and are basedupon ambient conditions of 12.35 psi absolute pressure and a roomtemperature of 75° C. The PVDF Meissner filter yielded a significantimprovement with the added vacuum. Specifically, at a 0.5 psibackpressure, the gas flow through the filter increased from 208 slpm upto 430 slpm which is an increase of 207%. The PE Zenpure filter yieldedan even more significant improvement. Specifically, at a 0.5 psibackpressure, the gas flow through the filter increased from 58 slpm to290 slpm which is an increase of 500%.

The results demonstrate significant improvements over normal flowfiltration and do confirm the potential for both cost savings andimproved performance. Operating this system at sea level would likelyimprove performance up to 16% compared to the 4200 foot elevation of thetest laboratory. It should also be recognized that a larger vacuum pumpcapable of a larger mass flow rate will prove beneficial during scale-upand likely be able to support >1000 slpm of airflow with a 10 inchfilter length while operating a back pressure less than the desiredprocess limit of 0.5 psi backpressure.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

What is claimed is:
 1. A method for filtering a gas, the methodcomprising: delivering a gas into a compartment of a gas filterassembly; applying a partial vacuum to the gas filter assembly so thatthe partial vacuum assists in drawing the gas through a porous filterbody of the gas filter assembly that is at least partially disposedwithin the compartment of the gas filter assembly; and regulating theapplication of the partial vacuum based on a pressure reading of the gasupstream of the gas filter assembly.
 2. The method for filtering asrecited in claim 1, wherein the application of the partial vacuum isautomatically regulated based on the pressure reading of the gasupstream of the gas filter assembly.
 3. The method for filtering asrecited in claim 1, further comprising sparging the gas through a liquidwithin a compartment of a container prior to delivering the gas into thecompartment of the gas filter assembly.
 4. The method for filtering asrecited in claim 3, further comprising regulating the application of thepartial vacuum based on a sensed value of the pressure reading of thegas within the container.
 5. The method for filtering as recited inclaim 3, wherein the liquid comprises a culture that includes media andcells or microorganisms suspended therein and the container comprises abioreactor.
 6. The method for filtering as recited in claim 1, furthercomprising passing the gas through a condenser assembly to removemoisture from the gas prior to delivering the gas into the compartmentof a gas filter assembly.
 7. The method for filtering as recited inclaim 6, wherein the condenser assembly comprises a flexible bag throughwhich the gas is passed.
 8. The method for filtering as recited in claim1, wherein the filter body of the gas filter assembly has a pore size of0.22 micometers (μm) or smaller.
 9. The method for filtering as recitedin claim 1, further comprising activating a heating element secured tothe gas filter assembly to heat the gas passing through the gas filterassembly.
 10. The method for filtering as recited in claim 1, whereinthe casing of the gas filter assembly comprises a flexible, collapsiblebag.
 11. A method for filtering a gas, the method comprising: sparging agas through a liquid within a compartment of a container; passing thesparged gas from the container through a gas filter; applying a partialvacuum to the gas filter so that the partial vacuum assists in drawingthe sparged gas through the gas filter; and regulating the applicationof the partial vacuum based on a pressure reading of the gas upstream ofthe gas filter.
 12. The method for filtering as recited in claim 11,wherein the application of the partial vacuum is automatically regulatedbased on the pressure reading of the gas upstream of the gas filter. 13.The method for filtering as recited in claim 11, wherein the applicationof the partial vacuum is regulated based on the pressure reading of thegas within the compartment of the container.
 14. The method forfiltering as recited in claim 11, wherein the liquid comprises a culturethat includes media and cells or microorganisms suspended therein. 15.The method for filtering as recited in claim 11, wherein the gas filteris at least partially disposed within a compartment of the casing, thecasing being comprised of a flexible sheet of a polymeric film.
 16. Themethod for filtering as recited in claim 11, further comprising: passingthe sparged gas from the container through a plurality of gas filters,the plurality of gas filters being disposed in parallel with each other,the gas filter being one of the plurality of gas filters; and applyingthe partial vacuum to each of the plurality of gas filters so that thepartial vacuum assists in drawing the gas through the plurality of gasfilters.
 17. The method for filtering as recited in claim 11, furthercomprising passing sparged gas through a condenser assembly to removemoisture from the gas prior to passing the gas through the gas filter.18. A system for filtering a gas comprising: a container having acompartment configured to hold a liquid and a gas; a gas filter coupledto the container so that gas can pass from the compartment of thecontainer to the gas filter; a first vacuum pump coupled with the gasfilter so that when the first vacuum pump is activated a partial vacuumis produced that assists in drawing gas from the container through thefirst gas filter assembly; a pressure sensor positioned to sense a gaspressure within the compartment of the container; and a computerprocessor in electrical communication with the pressure sensor andeither the first vacuum pump or a control valve disposed in fluidcommunication between the gas filter and the first vacuum pump.
 19. Thesystem as recited in claim 18, further comprising a liquid disposedwithin the compartment of the container, liquid comprises a culture thatincludes media and cells or microorganisms suspended therein and thecontainer comprises a bioreactor.
 20. The system as recited in claim 18,further comprising a condenser assembly coupled with the container sothat gas passing from the container to the gas filter passes through thecondenser assembly.